Page:Popular Science Monthly Volume 33.djvu/602

584 asexual multiplication by buds, and the sign < sexual reproduction by fertilized eggs:

The egg hatches into a planula, which becomes attached and is converted into a root, from which feeding hydras bud; from the roots of these feeding hydras, other feeding hydras, and, after a time, defensive hydras and blastostyles or reproductive hydras, are budded in very great numbers, and, while the diagram correctly represents the complexity of the colony, it conveys no conception of its size or of the number of its members. Each blastostyle produces a considerable number of buds, which are ultimately set free as swimming jelly-fish or Medusæ, and each medusa multiplies by budding, and thus gives rise to a second generation of Medusæ, which probably repeat the process in their turn, so that a very great and practically unlimited number of sexual egg-producing adults results from a single egg.

What a contrast between the direct and simple history of ordinary animals, where each adult is the total progeny of the egg, and such a life-history as this, where the egg not only produces an unlimited number of sexual adults able to bud off others like themselves, but also gives rise to an innumerable number of larvæ which never become sexually mature nor assume the adult form.

Those who are familiar with the subject know how much paper and ink have been wasted in discussing the individuality of hydroids, but we need not enter into into this dead issue, for, beyond question, each feeding hydra, each defensive hydra, each blastostyle, and each jelly-fish is an individual in the same sense that a horse or a dog is one; and the most remarkable peculiarity of Dysmorphosa is the enormously great number of descendants from each egg. Another peculiarity must also be noted. The